Detoxicating and silencing device



Feb. 10, 1970 v I 3,494,445 1 'lDETO IJKICATING AND siL'E'uome' DEVICEFiled July 7, 196'? v 2 Sheets-Sheet 1 Inventor:

, Feb..1o,197o "w. on 3,494,445

DETOXICATING AND SILENCI NG DEVICE Filed July 7. 1967 1 I z sheets-sne et 2 invnlor:

United States Patent US. Cl. 181-43 Claims ABSTRACT OF THE DISCLOSUREDetoxicating and silencing devices for pulsating gas flows such as theexhaust gases from internal combination engines. Each devices comprisesan elongated casing which is bulbous at one end and tapers towards acylindrical portion at the other end. Gas enters said casing through atangentially disposed inlet conduit.

The present invention relates to detoxica'ting and silencing devicesprimarily for detoxicating and silencing a pulsating flow of generallygaseous materials under elevated pressure, such as the exhaust gasesfrom internal combustion engines.

A prior proposal in this field was based on the recognition that,according to the basic laws of conical sections, a line passing throughthe focal point of a parabola is reflected back at the Wall of theparabola parallel to the focal axis of the parabola so that, whenrelated to the three dimensional system of a paraboloid, a stream of gaswhich is allowed to issue at or near the focal point is redirectedparallel to the focal axis and axis of symmetry of the paraboloid whichis formed as a rotational shape around this axis. For the same reasonhollow ellipsoids have been proposed so that when a stream of gas issuesnear one of the two focal points and is reflected by the wall, it isre-directed to the other focal point. It was proposed that suchreflections within a paraboloid or ellipsoid could result indisplacements of the frequencies of the sound vibrations relative to oneanother so that at least a partial cancellation of sound, or silencing,would result.

It has also been proposed to construct exhaust silencers so as not onlyto silence but also to detoxicate the exhaust gases. According to thatproposal the silencer easing is constructed essentially in the form of ahollow egg with input and output conduits arranged at specified anglesso that the exhaust gas stream is formed into a three dimensional spiralhaving an extraordinarily high vortical speed in the vicinity of the tipof the egg. Under the influence of this movement, thermochemicaldecomposition takes place which at least partially detoxicates thegases. In one example there was achieved a lowering of the CO contentfrom 9.3% to 3.4%, or from 9.4% to 2.8%. At the same time the CO contentrose from 8.5% to 12.4% when idling, and from 8.0% to 11.3% when underfull load. The H content dropped from 4.2% to 1.3% when idling and from4.3% to 1.1% under full load. CH and other hydrocarbon contents could nolonger be detected. Only in special cases was the introduction ofoxygen, optionally in the form of atmospheric oxygen, or other reagentsrequired in order to achieve similar favourable conditions.

However on practical operation of such previously proposed devices ithas been found that they are highly sensitive and that optimum values ofdetoxication and silencing can only be achieved if they are relativelyaccurately rnatched to the particular prevailing motor conditions asregards volume or size, construction and arrangement.

It is the object of the present invention to provide a detoxicating andsilencing device which basically retains 3,494,445 Patented F eh. 10,1970 the advantages presented above, but which in addition is relativelyinsensitive to particular conditions, i.e. is relatively independent ofthe nature, size and construction of the internal combustion engine orother source of exhaust gases which precedes it.

According to the present invention, there is provided a device primarilyfor detoxicating and silencing a pulsating flow of generally gaseousmaterial under elevated pressure, such as the exhaust gases from aninternal combustion engine, comprising an elongated casing which isgenerally bulbous at one end and tapers towards a substantiallycylindrical portion at the other end, an input conduit for generallygaseous material communicating substantially tangentially with theinterior of said casing at the bulbous end thereof, said cylindricalportion defining an output conduit, wherein, over the region of thecasing lying substantially between the input conduit and said other endof the casing, the line of intersection of the casing with any planeincluding the longitudinal centreline of the casing is a second orhigher order or transcendent curve convex towards said centre-line.

A particularly effective construction of the device results if saidsecond order curve is part of a hyperbola.

Preferably, said region of the casing is a hollow body of revolutionaxially symmetrical about the longitudinal centre-line, one said line ofintersection serving as the generatrix of the body.

There is greater freedom of choice as regards the possible shape of asecond region of the casing lying substantially between the inputconduit and said one end of the casing, i.e. normally the region lyingbetween the boundary of the first region and said one end of the casing.Over this second region, the line of intersection of the casing with anyplane including the longitudinal centre-line of the casing is preferablya second order curve concave towards said centre-line. Said second orderconcave curve may optionally be circular, elliptical, parabolic orogival.

An injector conduit may be provided communicating with the interior ofthe casing at the bulbous end thereof. Such a conduit is for the supplyof a flow of generally gaseous working materials such as air, steam,oxygen-enriched air or oxygen. This conduit is suitably co-axial withthe longitudinal centre-line of the casing. This addition of workingmaterials, even air, results in an improvement of the detoxicatingproperties of the silencer in that the carbon monoxide content abruptlydrops below the limit which according to present experience is stillpermissible without leading to the level of atmospheric pollution atwhich health damage can occur.

Two embodiments of the invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal section through a detoxicating and silencingdevice constructed in accordance with the invention, and

FIG. 2 illustrates the arrangement for a double-piston motor with twoopposed cylinders.

Referring to FIG. 1, there is shown an input conduit for the exhaustgases from an internal combustion engine. The conduit 1 communicatesgenerally tangentially with the interior of a casing 2 through theaperture 3. The axis 44 of the conduit 1 makes an acute angle 7 with aplane marked 5-5 which extends perpendicular to the longitudinalcentre-line 66 of the silencer casing 2.

The casing 2 is in the form of a hollow hemi-sphere 8 and part of ahollow hyperboloid 9 which is generated as a body of rotation about theaxis 6-6 by rotation of the generatrix hyperbola 1t 10 about the axis66, which is the axis of symmetry. The casing sections 8 and 9 mergewith one another at 11 without a step or discontinuity.

working materials ends within the part 8 of the casing and is co-axialwith the centre-line 6-6. In general, supply of air in the direction ofthe arrow 13 suffices. The conduit 12 projects somewhat beyond thecasing section 8 inside the silencer, with flared guide surfaces 14being provided to assist occurrence of an injector effect andwhichresults in it not being necessary to introduce the additional workingmaterials under excess pressure. This does not exclude the use of excesspressure, especially not in the case of water, for example, beingsprayed in or a post-combustion being carried out.

Referring now to FIG. 2 there is shown an arrangement of two silencers15, 16, constructed in accordance with the invention, in conjunctionwith a double-piston internal combustion engine having a crank casing 17and cylinders or cylinder rows 18 and 19. The axes of these cylindersare arranged about the crank circle displaced by 180. This leads to theillustrated possibility of so arranging the exhaust gas input conduits20, 21 between the cylinder heads 22, 23 and the silencer casings 15, 16that they run essentially parallel to one another. At the same time thecentre-lines of the silencers cross so that it is possible to arrange,with relatively little space requirement, for the output conduits 24, 25for the largely detoxicated exhaust gases to extend in the usual manner.

*It has been found that a device constructed as shown in FIG. 1 leads tosignificant insensitivity to particular conditions as regards theprecise nature, size and construction of the internal combustion enginewith which it is associated in operation. At the same time significantadvantageous as regards detoxication and silencing were found. In oneexample the CO content dropped to 0.5% or 0.6% when idling. When air wasintroduced through conduit 12 the CO content dropped to 0.3% or 0.4%. At4000 r.p.m. the figure was as low as 2.3% or 2.2% without addition ofair and 0.7% or 0.6% with the addition of air. At 2000 rpm. the COcontent was 1.9% without and 0.5% with air. At the same time the fuelconsumption of the engine was reduced by from 15% to 25%. Measurement ofthe decibels also indicated that the silencing ability was very good.Moreover the exhaust and coolant temperatures of the engine showed noincrease.

The above eifects areattributable to the fact that in order to constrainthe stream of exhaust gases to flow in the form of a three-dimensionalhelix of reducing diameter, as shown at 26 in FIG. 1, a relatively highproportion of the gas stream energy is absorbed, so that the exhaustnoise is greatly dampened. At the same time, the high vortical speeds,in conjunction with the temperature at which the silencer operates, leadto the abovementioned thermo-chemical detoxicating reactions. Thesereactions may be further favoured by thermal insulation of the silencercasing and by constructing the casing of bright iron, whereby to exert acatalytic effect to favour these reactions.

I claim: I

1. A device primarily for detoxicating and silencing a pulsating flow ofgenerally gaseous material under elevated pressure, such as the exhaustgases from an internal combustion engine, comprising an elongated casingwhich is generally bulbous at one end and tapers towards a substantiallycylindrical portion at the other end, an input conduit for generallygaseous material communicating substantially tangentially with theinterior of said casing at the bulbous end thereof, said cylindricalportion defining an output conduit, wherein, over the region of thecasing lying substantially between the input conduit'and said other endof the casing, the line of intersection of the casing with any planeincluding the longitudinal centreline of the casing is a second orhigher order or transcendent curve convex towards said centre-line.

2. A device according to claim 1 wherein said second order curve is partof a hyperbola.

3. A device according to claim 1 wherein over at least said region, thecasing is a hollow body of revolution axially symmetrical about thelongitudinal centre-line, one said line of intersection serving as thegeneratrix of the body.

4. A device according to claim 1 wherein, over a second region of thecavity lying substantially between the input conduit and said one end ofthe casing, the line of intersection of the casing with any planeincluding the longitudinal centre-line of the casing is a second ordercurve concave towards said centre-line.

5. A device according to claim 4 wherein said second order concave curveis part of a circle.

6. A device according to claim 4 wherein said second order concave curveis part of an ellipse.

7. A device according to claim 4 wherein said second order concave curveis part of a parabola.

8. A device according to claim 4 wherein said second order concave curveis ogival.

9. A device according to claim 1 including an injector conduit for thesupply of a flow of generally gaseous additional workin g materials,said conduit communicating with the interior of said casing at thebulbous end thereof coaxially with the longitudinal centre-line of thecasing.

10. Apparatus primarily for detoxicating and silencing two or morepulsating flows of generally gaseous material under elevated pressure,such as the exhaust gases from a multi-cylinder internal combustionengine having cylinders or rows of cylinders displaced about a crankcircle, comprising a plurality of devices, each device being associatedwith one said displaced cylinder and each device comprising an elongatedcasing which is generally bulbous at one end and tapers towards asubstantially cylindrical portion at the other end, an input conduit forgenerally gaseous material communicating substantially tangentially withthe interior of said casing at the bulbous end thereof, said cylindricalportion defining an output conduit, wherein, over the region of thecasing lying substantially between the input conduit and said other endof the casing, the line of intersection of the casing with any planeincluding the longitudinal centre-line of the casing is a second ordercurve convex towards said centre-line, and wherein the devices aredisposed with their longitudinal centre-lines lying at an angle to oneanother in spaced planes, the input conduits extending substantiallyparallel to one another.

References Cited UNITED STATES PATENTS 940,031 11/1909 Krotz. 1,217,0212/1917 Lebedefl' 181-51 1,564,931 12/1925 Boysen 181-58 2,057,30410/1936 Saint-Jacques 181-58 2,370,259 2/ 1945 Rippingille. 2,386,30510/ 1945 Flickinger 181-43 FOREIGN PATENTS 17,282 1/ 1930 Australia.573,669 3/ 1924 France. 592,649 5/ 1925 France. 639,486 3/ 1928 France.

ROBERT S. WARD, JR., Primary Examiner U.S. Cl. X.R. 181-40, 58, 60

